1. Field of the Invention
This invention relates to a collar adapted for use with pre-filled cartridge-needle units and disposable holders to form a syringe assembly.
2. Description of the Prior Art
Disposable medicament-containing cartridge needle units for use in conjunction with reusable hypodermic syringe holders are well known in the art and in widespread commercial use. Such cartridges conventionally feature a cylindrical body closed at the proximal end with a flexible plunger slidable within the bore of the cartridge and closed at the distal necked-down end with a septum secured to the cartridge by a crimped-on aluminum collar. The necked-down distal end conventionally is fitted with a needle hub/needle/sheath assembly. Such cartridge-needle units are available from Sanofi Winthrop Pharmaceuticals under the Carpuject.RTM. trademark.
In use, the cartridge-needle unit must be activated, i.e., the proximal end of the needle cannula must penetrate the sealed septum such that communication is achieved between the fluid and the proximal end of the needle. Some cartridge-needle units are sold in an activated form. Others must be activated by the user. When user activated cartridge-needle units are used in conjunction with conventional reusable syringe holders of the type described, for example, in Hadtke, U.S. Pat. No. 4,585,445 and in EP-A 485,028, this is accomplished when the health care worker advances the cartridge through the holder by rotating a clamping element.
Many holders, including the above-referenced reusable holders, enable the user to avoid handling the cartridge-needle unit when the needle unit is exposed. Nevertheless, health care workers are especially susceptible to accidental and potentially infectious, and indeed, on occasion, possibly fatal, needle strikes due to the careless handling and/or disposing of the cartridge-needle unit after use. The consequences to health care workers of strikes from needles contaminated with various infectious diseases such as hepatitis or AIDS can be particularly severe. The frequency of such accidental needle strikes in the United States is surprisingly great, and has been estimated to be approximately one million strikes per year. Moreover, the cost to health care organizations for the testing of health care workers accidentally stricken by used needles is a significant burden on health care costs. Therefore, it would be desirable to further protect health care workers by providing systems which reduce the possibility of accidental needle strikes.
To this end, it has been suggested to provide a hollow body to house the cartridge-needle unit, such that the needle can be exposed for use and then withdrawn into the body for safety. For example, PCT/US91/06878 describes disposable, i.e., single use, holders which can be used in conjunction with cartridge-needle units. This system features a holder containing a radially deformable body having an elliptical cross-section; and an adapter having a circumferentially extending adapter ring sized to engage specifically positioned pairs of body slots formed in the body. However, in practice, the adapter designs proposed in PCT/US91/06878 function less than satisfactorily and result in unacceptable safety and reliability risks during use. For example, the prior art adapters do not adequately retain the needle hub. This can lead to failures when the cartridge-needle unit is thrust forward by the user during activation and delivery, or during retraction. Further, the proposed prior art adapter designs significantly increase the force required to activate the cartridge-needle unit, which can lead to failure of the syringe assembly to function for its intended purpose. Additionally, it is virtually impossible to manufacture the prior art adapters in a manner that would enable the syringe assemblies to be sold at a price which would enable them to be competitive in significant segments of the market. Consequently, these systems are less than fully satisfactory from a commercial standpoint.
In addition, existing safety syringe systems often are not economical to manufacture and/or assemble in large quantities. This is especially true when the syringe system is intended to be disposable.
It would be desirable to provide an improved collar for use with a cartridge-needle unit and holder which enables the system to be assembled and used safely and easily and which reduces the susceptibility of health care workers to accidental needle strikes.